The present invention relates to dynamoelectric machines and more particularly, to motors having counterbalanced rotors used to balance customer compressors. The invention provides for a method of forming weights that attach to a rotor to offset the weight of customer or application components. While the invention is described in particular detail with respect to its use in compression assemblies, those skilled in the art will recognize the wider applicability of the invention disclosed hereinafter.
Counterbalanced rotors are old in the art. Rotors are balanced to offset the inertial load produced from attaching customer or application components to the motor with which the rotor is associated. An imbalance in such an assembly causes excessive vibration and vibration induced noises. A properly balanced rotor minimizes these vibrational effects. Weights are secured to the rotor to counterbalance the components. Several attempts have been made to form weights for counterbalancing rotors. The counterbalancing weights are often formed from stamped steel. The shapes produced by using stamped steel weights are limited to flat sections. The material is too rigid to produce shapes with intricate features. As a result, weight manipulation of stamp steel is difficult when minute alterations are required. The weight is manipulated by adding holes or grooves to the weights. This process includes drilling and sometimes filling holes in the weights, which is cumbersome and time consuming. Another method of forming counterbalanced rotors is by adding die-cast weights to the rotor. The weights are die-cast from metals including zinc and bronze. This method also limits weight manipulation of the rotor by drilling and filling holes in the weights. In addition, die-casting precludes incorporation of intricate features on the weights that provide for anti-rotation and shear resistance between the weights and the rotor.